JP3116093B1 - Method for producing TiO single crystal thin film - Google Patents

Abstract

A TiO single crystal thin film is obtained. SOLUTION: Ti is vacuum-deposited on an MgO single-crystal substrate, and then the substrate is heated to produce a metal salt conductive TiO as a single-crystal thin film having a rock salt type crystal structure on the MgO substrate. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a TiO single crystal thin film, and more particularly to a TiO single crystal thin film formed on a MgO single crystal substrate and a method for producing the same.

[0002]

2. Description of the Related Art Titanium oxide has several stable phases. Among them, TiO has metallic conductivity and also has excellent properties as a material such as high strength and high melting point. TiO has also attracted attention as a catalyst.

[0003] It is known that a thin film of titanium oxide is usually formed by a vacuum deposition method using titanium oxide as a raw material or a sputtering method using a target of titanic acid. In addition, a method of forming a thin film of titanic acid or a substance on a magnesium oxide substrate by treating a gas containing an organic titanium compound under the generation of plasma by high-frequency discharge is also known (JP-A-4-219317, JP-A-6-219). 3404
No. 22).

[0004]

SUMMARY OF THE INVENTION TiO is a non-stoichiometric compound and has not been obtained as a single crystal until now. Therefore, there is a strong demand for a technique for manufacturing a TiO single crystal thin film whose composition and structure are well controlled.

[0005]

Means for Solving the Problems The present inventors utilize the interfacial reaction between the Ti-deposited film and the surface of the MgO substrate to form a TiO.
The present invention has found that a single-crystal thin film can be formed, and provides a method for manufacturing a TiO single-crystal thin film on an MgO single-crystal substrate.

That is, the present invention provides a rock salt type crystal structure, a metallic conductivity, and a TiO crystal on a MgO single crystal substrate.
This is a method for producing a TiO single crystal thin film formed by the internal diffusion reaction.

TiO exhibits electrical conductivity based on a metallic electronic structure in which the Fermi level is in the conduction band. Therefore, the well-defined Ti on the transparent insulator MgO
If an O single crystal thin film is formed, for example, applications such as a transparent electrode are expected.

[0008] In the interfacial reaction between Ti and MgO used to form a TiO single crystal thin film in the present invention, Mg
The Ti deposited on the O single crystal substrate is diffused inside through the Mg substitution position of MgO. The internal diffusion of Ti is activated by the heat treatment of the substrate.

In the present invention, TiO having the same rock salt type crystal structure as MgO and having the same lattice constant (4.18 °) as that of MgO (4.21 °) is utilized by utilizing such an interface reaction mechanism. Was prepared.

According to the present invention, Ti is vapor-deposited on an MgO single-crystal substrate, and then the substrate is heated to 800 to 1000 K, which is the internal diffusion temperature of Ti, in a vacuum. A TiO single-crystal thin film by growing a TiO single-crystal thin film by inwardly diffusing through a Mg-substituted position of MgO.

As the MgO single crystal substrate, a single crystal substrate of MgO in the atmosphere is used. Since the TiO single crystal thin film is based on the interface reaction between the deposited Ti and the MgO surface, the contaminant layer on the MgO surface formed by contact with the air must be removed in advance by a cleaning method. Is desirable. Known methods can be used for the method of vacuum deposition of Ti itself. However, when the substrate is heated to the internal diffusion temperature after vacuum deposition, the temperature of the MgO single crystal substrate may be room temperature.

The temperature for heating to the internal diffusion temperature is 800 to
A temperature of about 1000K is preferable, but the best quality TiO single crystal thin film can be obtained at a temperature of 1000K. Also,
The introduction of oxygen into the vacuum during heating at the internal diffusion
It degrades the quality of the single crystal thin film. Therefore, heating at the internal diffusion temperature needs to be performed in a vacuum.

Further, the present invention relates to a single crystal substrate of MgO
By vacuum-depositing Ti while maintaining the temperature at 0 to 800 K, the Ti deposited on the MgO single crystal substrate is internally diffused through the Mg substitution position of MgO to grow a TiO single crystal thin film. This is a method for producing a TiO single crystal thin film. When performing Ti vapor deposition while maintaining the substrate temperature at a high temperature of 500 to 800 K, the same good quality as a TiO single crystal thin film formed by room temperature vapor deposition without performing heating at the internal diffusion temperature after vapor deposition. A TiO single crystal thin film is obtained.

[0014]

Embodiment 1 Hereinafter, the present invention will be described in detail with reference to the illustrated embodiment. M
The gO single crystal substrate was formed by cleaving a single crystal of MgO in the atmosphere. At this time, the surface of the substrate is parallel to (001), but this MgO (001) substrate is
For 10 minutes to clean the surface.

An MgO (001) single crystal substrate was prepared.
Then, vacuum evaporation equipped with a Ti evaporation source using the electron impact method
While maintaining the substrate temperature at room temperature using a deposition apparatus,
× 10 ^-9Vacuum deposited at 10 A in Torr vacuum. Further
Then, the MgO (001) substrate on which Ti was deposited was
Internal diffusion temperature at 1000K for 10 minutes in a vacuum deposition apparatus
To form a TiO single crystal thin film. After Ti deposition
Due to the heating at the internal diffusion temperature, the deposited Ti becomes MgO
Promotes interfacial reaction that diffuses into the substrate through the Mg-substituted position
And a high quality TiO single crystal thin film was obtained.

FIGS. 1 (a) and 1 (b) show MgO (0
01) Reflection high-speed electron diffraction pattern from the surface, and FIGS. 1C and 1D are reflection high-speed electron diffraction patterns of the obtained TiO single crystal thin film.

The incident electron beam azimuth in the reflection high-energy electron diffraction is [100] in FIGS. 1A and 1C and [110] in FIGS. 1B and 1D. From the reciprocal lattice rod interval in the reflection high-energy electron diffraction pattern of FIG. 1, the lattice constant of the surface corresponding to FIGS. 1C and 1D is 4.1.
It can be seen that a single crystal thin film of 8A is growing, which corresponds to the lattice constant of TiO.

FIG. 2 shows the energy spectrum of Li ⁺ direct impact ion scattering spectroscopy obtained on the surfaces corresponding to FIGS. 1 (c) and 1 (d). From the energy spectrum of FIG. 2, the surface corresponding to (c) and (d) of FIG.
It can be seen that it is composed of i and O. That is, FIG.
From FIG. 2 and FIG. 2, Ti was vapor-deposited on a MgO (001) surface at room temperature at 10 A in an ultra-high vacuum, and then the substrate was similarly heated at 1000 K for 10 minutes at an internal diffusion temperature in an ultra-high vacuum. This indicates that a crystalline thin film has been formed.

At this time, the orientation relationship between the upper TiO single crystal thin film and the underlying MgO single crystal substrate is TiO (00
1) // MgO (001), TiO [100] // Mg
O [100]. The formation of such a TiO single crystal thin film was confirmed when the Ti film thickness was in the range of 10 to 100A.

FIG. 3 is a graph showing the results of Li ⁺ direct impact ion scattering spectroscopy of Ti observed on the surfaces corresponding to FIGS. 1 (c) and (d).
5 shows the results of examining the intensity of Ti in O as a function of incident angle in [100] and [110] directions. In the spectrum of FIG. 3, all peaks are explained by a focusing effect in ion scattering using a rock salt type crystal structure, and the TiO single crystal thin films corresponding to FIGS. 1 (c) and (d) have a rock salt type crystal structure. Is shown to have

FIG. 4 shows the spectra of metastable He * atom deexcitation spectroscopy observed on the surfaces corresponding to FIGS. 1 (c) and 1 (d). In FIG. 4, a sharp peak near the Fermi level indicates that the outermost surface of the TiO single crystal thin film has metallic properties.

Example 2 An MgO (001) single crystal substrate was prepared in the same manner as in Example 1, and then Ti was deposited while maintaining the substrate temperature at 500K. In this case, a high-quality single-crystal thin film similar to a TiO single-crystal thin film formed by deposition at room temperature was obtained without performing heating at the internal diffusion temperature after the deposition.

[Brief description of the drawings]

FIG. 1 is a drawing substitute photograph showing a reflection high-energy electron diffraction pattern, in which (a) and (b) are from the surface of a MgO (001) single crystal substrate, and (c) and (d) are , MgO (0
01) Obtained from the surface of a TiO single crystal thin film formed on the surface of a single crystal substrate.

FIG. 2 is a graph showing an energy spectrum of Li ⁺ direct impact ion scattering spectroscopy observed on a TiO single crystal thin film formed on the surface of a MgO (001) single crystal substrate.

FIG. 3 is an incidence angle of Li ⁺ direct collision ion scattering spectroscopy observed in [100] and [110] directions observed in a TiO single crystal thin film formed on the surface of a MgO (001) single crystal substrate. It is a graph which shows a decomposition measurement result.

FIG. 4 shows metastable H observed in a TiO single crystal thin film formed on the surface of a MgO (001) single crystal substrate.
It is a graph which shows e * atom deexcitation spectroscopy spectrum.

──────────────────────────────────────────────────続 き Continued on the front page (56) References Suzuki et al. J., "Interfacial Reaction During Thin Film Growth of Tion the MgO (001) Surface," J. Am. Phys. Chem. B, 1999. Vol. 103 pp. 5747-5749 (58) Field surveyed (Int. Cl. ⁷ , DB name) C30B 1/00-35/00 CA (STN)

Claims (2)

(57) [Claims] 1. After vacuum-depositing Ti on an MgO single-crystal substrate, the substrate is placed in a vacuum at a temperature of 800 to 200 ° C., which is the internal diffusion temperature of Ti.
A method for producing a TiO single crystal thin film, characterized in that Ti deposited on an MgO single crystal substrate is internally diffused through a Mg substitution position of MgO by heating to 1000 K to grow a TiO single crystal thin film. 2. By vacuum-depositing Ti while maintaining the MgO single crystal substrate at a temperature of 500 to 800K,
A method for producing a TiO single-crystal thin film, wherein Ti deposited on an MgO single-crystal substrate is internally diffused through a Mg-substituted position of MgO to grow a TiO single-crystal thin film.